Methods for manufacturing bulked continuous filament

ABSTRACT

A method of recycling a PET-containing material comprises: (1) providing a polymer crystallizer comprising at least one heating element, and at least one blower; (2) providing an MRS extruder having an MRS section comprising a plurality of satellite screws; (3) providing a vacuum pump in fluid communication with the MRS section; (4) grinding and washing the PET-containing material; (5) heating the PET-containing material in the crystallizer to at least partially dry the PET-containing material; (6) shearing the PET-containing material in the MRS extruder to produce a PET-containing melt; (7) increasing a surface area of the PET-containing melt by distributing the PET-containing melt across a plurality of satellite screws in the MRS extruder; (8) drawing off vapors from the PET-containing melt by reducing the pressure in the MRS section with the vacuum pump; (9) collating the PET-containing melt in the MRS extruder; and (10) extruding a recycled PET-containing material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/866,702, filed May 5, 2020, entitled “Methods for ManufacturingBulked Continuous Filament,” which is a continuation of U.S. patentapplication Ser. No. 16/213,694, filed Dec. 7, 2018, now U.S. Pat. No.10,647,046, issued May 12, 2020, entitled “Methods for ManufacturingBulked Continuous Filament,” which is a continuation of U.S. patentapplication Ser. No. 15/473,385, filed Mar. 29, 2017, now U.S. Pat. No.10,239,247, issued Mar. 26, 2019, entitled “Systems and Methods forManufacturing Bulked Continuous Filament,” which is a continuation ofU.S. patent application Ser. No. 14/546,796, filed Nov. 18, 2014, nowU.S. Pat. No. 9,636,860, issued May 2, 2017, entitled “Method ofManufacturing Bulked Continuous Filament,” which is acontinuation-in-part of U.S. patent application Ser. No. 13/892,740,filed May 13, 2013, now abandoned, entitled “Systems and Methods forManufacturing Bulked Continuous Filament,” which is a divisional of U.S.patent application Ser. No. 13/721,955, filed Dec. 20, 2012, now U.S.Pat. No. 8,597,553, issued Dec. 3, 2013, entitled “Systems and Methodsfor Manufacturing Bulked Continuous Filament,” which claimed the benefitof U.S. Provisional Patent Application Ser. No. 61/654,016, filed May31, 2012, entitled “Systems and Methods for Manufacturing BulkedContinuous Fiber,” all of which are hereby incorporated herein byreference in their entirety.

BACKGROUND

Because pure virgin PET polymer is more expensive than recycled PETpolymer, and because of the environmental benefits associated with usingrecycled polymer, it would be desirable to be able to produce bulkedcontinuous carpet filament, and other items, from 100% recycled PETpolymer (e.g., PET polymer from post-consumer PET bottles).

SUMMARY

A method of recycling a PET-containing material, according to variousembodiments, comprises: (1) providing a polymer crystallizer comprisingat least one heating element, and at least one blower; (2) providing amulti-rotating screw (MRS) extruder having an MRS section comprising aplurality of satellite screws, each of the plurality of satellite screwsbeing at least partially housed within a respective extruder barrel andmounted to rotate about its respective central axis; (3) providing avacuum pump in fluid communication with the MRS section; (4) grindingand washing the PET-containing material; (5) heating the PET-containingmaterial in the crystallizer to at least partially dry thePET-containing material; (6) shearing the PET-containing material in theMRS extruder to produce a PET-containing melt; (7) increasing a surfacearea of the PET-containing melt by distributing the PET-containing meltacross the plurality of satellite screws in the MRS extruder; (8)drawing off vapors from the PET-containing melt by reducing the pressurein the MRS section with the vacuum pump; (9) collating thePET-containing melt in the MRS extruder; and (10) extruding a recycledPET-containing material.

In various embodiments, the PET-containing material is either old carpetor recycled PET bottles. In some embodiments, the pressure is reduced tobetween 0 and 25 millibars. In particular embodiments, the vapors aremoisture from interstitial water and volatile organic impurities. Insome embodiments, the moisture in the PET-containing melt is reduced tobelow about 50 ppm. In various embodiments, the vacuum pump is a jetvacuum pump.

A method of purifying a PET polymer, according to various embodiments,comprising: (1) grinding and washing a PET-containing material; (2)heating the PET-containing material in a crystallizer to at leastpartially dry the PET-containing material, wherein the crystallizercomprises at least one heating element, and at least one blower; (3)melting the PET-containing material in an MRS extruder, wherein the MRSextruder comprises a plurality of satellite screws, each of theplurality of satellite screws being at least partially housed within arespective extruder barrel and mounted to rotate about its respectivecentral axis, a viscosity monitor, and a pressure regulation system; (4)increasing a surface area of the melted PET-containing material bydistributing the PET-containing material across the plurality ofsatellite screws in the MRS extruder; (5) monitoring a viscosity of themelted PET-containing material within the MRS extruder; (6) regulating apressure within the MRS extruder with the pressure regulation system inresponse to an intrinsic viscosity of the PET-containing melt; (7)filtering the melted PET-containing material through a filter; and (8)extruding a purified PET polymer.

In various embodiments, the PET-containing material is either old carpetor recycled PET bottles. In particular embodiments, the pressure isreduced to between 0 and 25 millibars. In some embodiments, the pressureregulation system comprises a vacuum pump. In other embodiments, thevacuum pump is a jet vacuum pump. In a particular embodiment, the atleast one heating element is configured to maintain a temperature withinthe crystallizer to between about 100 degrees Fahrenheit and about 180degrees Fahrenheit. In some embodiments, the at least one heatingelement is configured to maintain a temperature within the crystallizerto between about 100 degrees Celsius and 180 degrees Celsius. In aparticular embodiment, the filter comprises a 40 micron screen filterfollowed by a 25 micron screen filter.

A method of using a purified polymer to produce bulked continuousfilament, according to various embodiments, comprises: (1) stirring andheating a plurality of washed polymer flakes in a crystallizer tosubstantially remove surface moisture from the plurality of washedpolymer flakes; (2) directly feeding the plurality of polymer flakes toan extruder and melting the plurality of polymer flakes to produce apolymer melt, wherein the extruder comprises a plurality of satellitescrews, each of the plurality of satellite screws being at leastpartially housed within a respective extruder barrel and mounted torotate about its respective central axis; (3) expanding a surface areaof the polymer melt by separating the polymer melt into a plurality ofstreams of polymer melt, wherein each stream of polymer melt isassociated with one satellite screw of the plurality of satellitescrews; (4) removing at least some water and volatile organic impuritiesfrom the plurality of streams of polymer melt by reducing a pressurewithin the extruder; (5) recombining the streams of polymer melt; (6)filtering the recombined polymer melt through a filter to produce apurified polymer melt; and (7) directly feeding the purified polymermelt into a spinning machine wherein the purified polymer melt is spuninto bulked continuous filament.

In some embodiments, the pressure regulation system is configured tomaintain the pressure to between 0 and 25 millibars. In otherembodiments, the pressure regulation system is configured to maintainthe pressure to between 0 and 18 millibars. the pressure regulationsystem comprises a vacuum pump. In various embodiments, the vacuum pumpis a jet vacuum pump. In some embodiments, the filter comprises a 40micron screen filter followed by a 25 micron screen filter.

BRIEF DESCRIPTION OF THE DRAWINGS

Having described various embodiments in general terms, reference willnow be made to the accompanying drawings, which are not necessarilydrawn to scale, and wherein:

FIG. 1 depicts a process flow, according to a particular embodiment, formanufacturing bulked continuous carpet filament.

FIG. 2 is a perspective view of an MRS extruder that is suitable for usein the process of FIG. 1.

FIG. 3 is a cross-sectional view of an exemplary MRS section of the MRSextruder of FIG. 2.

FIG. 4 depicts a process flow depicting the flow of polymer through anMRS extruder and filtration system according to a particular embodiment.

FIG. 5 is a high-level flow chart of a method, according to variousembodiments, of manufacturing bulked continuous carpet filament.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Various embodiments will now be described in greater detail. It shouldbe understood that the invention may be embodied in many different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided so that this disclosurewill be thorough and complete, and will fully convey the scope of theinvention to those skilled in the art. Like numbers refer to likeelements throughout.

I. Overview

New processes for making fiber from recycled polymer (e.g., recycled PETpolymer) are described below. In various embodiments, this new process:(1) is more effective than earlier processes in removing contaminatesand water from the recycled polymer; and/or (2) does not require thepolymer to be melted and cooled as many times as in earlier processes.In at least one embodiment, the improved process results in a recycledPET polymer having a polymer quality that is high enough that the PETpolymer may be used in producing bulked continuous carpet filament from100% recycled PET content (e.g., 100% from PET obtained from previouslyused PET bottles). In particular embodiments, the recycled PET polymerhas an intrinsic viscosity of at least about 0.79 dL/g (e.g., of betweenabout 0.79 dL/g and about 1.00 dL/g).

II. More Detailed Discussion

A BCF (bulked continuous filament) manufacturing process, according to aparticular embodiment, may generally be broken down into three steps:(1) preparing flakes of PET polymer from post-consumer bottles for usein the process; (2) passing the flakes through an extruder that meltsthe flakes and purifies the resulting PET polymer; and (3) feeding thepurified polymer into a spinning machine that turns the polymer intofilament for use in manufacturing carpets. These three steps aredescribed in greater detail below.

Step 1: Preparing Flakes of PET Polymer from Post-Consumer Bottles

In a particular embodiment, the step of preparing flakes of PET polymerfrom post-consumer bottles comprises: (A) sorting post-consumer PETbottles and grinding the bottles into flakes; (B) washing the flakes;and (C) identifying and removing any impurities or impure flakes.

A. Sorting Post-Consumer PET bottles and Grinding the Bottles intoFlakes

In particular embodiments, bales of clear and mixed colored recycledpost-consumer (e.g., “curbside”) PET bottles (or other containers)obtained from various recycling facilities make-up the post-consumer PETcontainers for use in the process. In other embodiments, the source ofthe post-consumer PET containers may be returned ‘deposit’ bottles(e.g., PET bottles whose price includes a deposit that is returned to acustomer when the customer returns the bottle after consuming thebottle's contents). The curbside or returned “post-consumer” or“recycled” containers may contain a small level of non-PET contaminates.The contaminants in the containers may include, for example, non-PETpolymeric contaminants (e.g., PVC, PLA, PP, PE, PS, PA, etc.), metal(e.g., ferrous and non-ferrous metal), paper, cardboard, sand, glass orother unwanted materials that may find their way into the collection ofrecycled PET. The non-PET contaminants may be removed from the desiredPET components, for example, through one or more of the variousprocesses described below.

In particular embodiments, smaller components and debris (e.g.,components and debris greater than 2 inches in size) are removed fromthe whole bottles via a rotating trammel. Various metal removal magnetsand eddy current systems may be incorporated into the process to removeany metal contaminants. Near Infra-Red optical sorting equipment such asthe NRT Multi Sort IR machine from Bulk Handling Systems Company ofEugene, Oreg., or the Spyder IR machine from National RecoveryTechnologies of Nashville, Tenn., may be utilized to remove any loosepolymeric contaminants that may be mixed in with the PET flakes (e.g.,PVC, PLA, PP, PE, PS, and PA). Additionally, automated X-ray sortingequipment such as a VINYLCYCLE machine from National RecoveryTechnologies of Nashville, Tenn. may be utilized to remove remaining PVCcontaminants.

In particular embodiments, a binary segregation of the clear materialsfrom the colored materials is achieved using automated color sortingequipment equipped with a camera detection system (e.g., a Multisort ESmachine from National Recovery Technologies of Nashville, Tenn.). Invarious embodiments, manual sorters are stationed at various points onthe line to remove contaminants not removed by the sorter and anycolored bottles. In particular embodiments, the sorted material is takenthrough a granulation step (e.g., using a 50B Granulator machine fromCumberland Engineering Corporation of New Berlin, Wis.) to size reduce(e.g., grind) the bottles down to a size of less than one half of aninch. In various embodiments, the bottle labels are removed from theresultant “dirty flake” (e.g., the PET flakes formed during thegranulation step) via an air separation system prior to entering thewash process.

B. Washing the Flakes

In particular embodiments, the “dirty flake” is then mixed into a seriesof wash tanks. As part of the wash process, in various embodiments, anaqueous density separation is utilized to separate the olefin bottlecaps (which may, for example, be present in the “dirty flake” asremnants from recycled PET bottles) from the higher specific gravity PETflakes. In particular embodiments, the flakes are washed in a heatedcaustic bath to about 190 degrees Fahrenheit. In particular embodiments,the caustic bath is maintained at a concentration of between about 0.6%and about 1.2% sodium hydroxide. In various embodiments, soapsurfactants as well as defoaming agents are added to the caustic bath,for example, to further increase the separation and cleaning of theflakes. A double rinse system then washes the caustic from the flakes.

In various embodiments, the flake is centrifugally dewatered and thendried with hot air to at least substantially remove any surfacemoisture. The resultant “clean flake” is then processed through anelectrostatic separation system (e.g., an electrostatic separator fromCarpco, Inc. of Jacksonville, Fla.) and a flake metal detection system(e.g., an MSS Metal Sorting System) to further remove any metalcontaminants that remain in the flake. In particular embodiments, an airseparation step removes any remaining label from the clean flake. Invarious embodiments, the flake is then taken through a flake colorsorting step (e.g., using an OPTIMIX machine from TSM Control Systems ofDundalk, Ireland) to remove any remaining color contaminants remainingin the flake. In various embodiments, an electro-optical flake sorterbased at least in part on Raman technology (e.g., a Powersort 200 fromUnisensor Sensorsysteme GmbH of Karlsruhe, Germany) performs the finalpolymer separation to remove any non-PET polymers remaining in theflake. This step may also further remove any remaining metalcontaminants and color contaminants.

In various embodiments, the combination of these steps deliverssubstantially clean (e.g., clean) PET bottle flake comprising less thanabout 50 parts per million PVC (e.g., 25 ppm PVC) and less than about 15parts per million metals for use in the downstream extrusion processdescribed below.

C. Identifying and Removing Impurities and Impure Flakes

In particular embodiments, after the flakes are washed, they are feddown a conveyor and scanned with a high-speed laser system 300. Invarious embodiments, particular lasers that make up the high-speed lasersystem 300 are configured to detect the presence of particularcontaminates (e.g., PVC or Aluminum). Flakes that are identified as notconsisting essentially of PET may be blown from the main stream offlakes with air jets. In various embodiments, the resulting level ofnon-PET flakes is less than 25 ppm.

In various embodiments, the system is adapted to ensure that the PETpolymer being processed into filament is substantially free of water(e.g., entirely free of water). In a particular embodiment, the flakesare placed into a pre-conditioner for between about 20 and about 40minutes (e.g., about 30 minutes) during which the pre-conditioner blowsthe surface water off of the flakes. In particular embodiments,interstitial water remains within the flakes. In various embodiments,these “wet” flakes (e.g., flakes comprising interstitial water) may thenbe fed into an extruder (e.g., as described in Step 2 below), whichincludes a vacuum setup designed to remove—among other things—theinterstitial water that remains present in the flakes following thequick-drying process described above.

Step 2: Using an Extrusion System to Melt and Purify PET Flakes

In particular embodiments, an extruder is used to turn the wet flakesdescribed above into a molten recycled PET polymer and to perform anumber of purification processes to prepare the polymer to be turnedinto BCF for carpet. As noted above, in various embodiments, after STEP1 is complete, the recycled PET polymer flakes are wet (e.g., surfacewater is substantially removed (e.g., fully removed) from the flakes,but interstitial water remains in the flakes). In particularembodiments, these wet flakes are fed into a Multiple Rotating Screw(“MRS”) extruder 400. In other embodiments, the wet flakes are fed intoany other suitable extruder (e.g., a twin screw extruder, a multiplescrew extruder, a planetary extruder, or any other suitable extrusionsystem). An exemplary MRS Extruder 400 is shown in FIGS. 2 and 3. Aparticular example of such an MRS extruder is described in U.S.Published Patent Application 2005/0047267, entitled “Extruder forProducing Molten Plastic Materials”, which was published on Mar. 3,2005, and which is hereby incorporated herein by reference.

As may be understood from this figure, in particular embodiments, theMRS extruder includes a first single-screw extruder section 410 forfeeding material into an MRS section 420 and a second single-screwextruder section 440 for transporting material away from the MRSsection.

In various embodiments, the wet flakes are fed directly into the MRSextruder 400 substantially immediately (e.g., immediately) following thewashing step described above (e.g., without drying the flakes orallowing the flakes to dry). In particular embodiments, a system thatfeeds the wet flakes directly into the MRS Extruder 400 substantiallyimmediately (e.g., immediately) following the washing step describedabove may consume about 20% less energy than a system that substantiallyfully pre-dries the flakes before extrusion (e.g., a system thatpre-dries the flakes by passing hot air over the wet flakes for aprolonged period of time). In various embodiments, a system that feedsthe wet flakes directly into the MRS Extruder 400 substantiallyimmediately (e.g., immediately) following the washing step describedabove avoids the need to wait a period of time (e.g., up to eight hours)generally required to fully dry the flakes (e.g., remove all of thesurface and interstitial water from the flakes).

FIG. 4 depicts a process flow that illustrates the various processesperformed by the MRS Extruder 400 in a particular embodiment. In theembodiment shown in this figure, the wet flakes are first fed throughthe MRS extruder's first single-screw extruder section 410, which may,for example, generate sufficient heat (e.g., via shearing) to at leastsubstantially melt (e.g., melt) the wet flakes.

The resultant polymer melt (e.g., comprising the melted flakes), invarious embodiments, is then fed into the extruder's MRS section 420, inwhich the extruder separates the melt flow into a plurality of differentstreams (e.g., 4, 6, 8, or more streams) through a plurality of openchambers. FIG. 3 shows a detailed cutaway view of an MRS Section 420according to a particular embodiment. In particular embodiments, such asthe embodiment shown in this figure, the MRS Section 420 separates themelt flow into eight different streams, which are subsequently fedthrough eight satellite screws 425A-H. As may be understood from FIG. 2,in particular embodiments, these satellite screws are substantiallyparallel (e.g., parallel) to one other and to a primary screw axis ofthe MRS Machine 400.

In the MRS section 420, in various embodiments, the satellite screws425A-H may, for example, rotate faster than (e.g., about four timesfaster than) in previous systems. As shown in FIG. 3, in particularembodiments: (1) the satellite screws 425A-H are arranged within asingle screw drum 428 that is mounted to rotate about its central axis;and (2) the satellite screws 425A-H are configured to rotate in adirection that is opposite to the direction in which the single screwdrum rotates 428. In various other embodiments, the satellite screws425A-H and the single screw drum 428 rotate in the same direction. Inparticular embodiments, the rotation of the satellite screws 425A-H isdriven by a ring gear. Also, in various embodiments, the single screwdrum 428 rotates about four times faster than each individual satellitescrew 425A-H. In certain embodiments, the satellite screws 425A-H rotateat substantially similar (e.g., the same) speeds.

In various embodiments, as may be understood from FIG. 4, the satellitescrews 425A-H are housed within respective extruder barrels, which may,for example be about 30% open to the outer chamber of the MRS section420. In particular embodiments, the rotation of the satellite screws425A-H and single screw drum 428 increases the surface exchange of thepolymer melt (e.g., exposes more surface area of the melted polymer tothe open chamber than in previous systems). In various embodiments, theMRS section 420 creates a melt surface area that is, for example,between about twenty and about thirty times greater than the meltsurface area created by a co-rotating twin screw extruder. In aparticular embodiment, the MRS section 420 creates a melt surface areathat is, for example, about twenty five times greater than the meltsurface area created by a co-rotating twin screw extruder

In various embodiments, the MRS extruder's MRS Section 420 is fittedwith a Vacuum Pump 430 that is attached to a vacuum attachment portion422 of the MRS section 420 so that the Vacuum Pump 430 is incommunication with the interior of the MRS section via a suitableopening 424 in the MRS section's housing. In still other embodiments,the MRS Section 420 is fitted with a series of Vacuum Pumps. Inparticular embodiments, the Vacuum Pump 430 is configured to reduce thepressure within the interior of the MRS Section 420 to a pressure thatis between about 0.5 millibars and about 5 millibars. In particularembodiments, the Vacuum Pump 430 is configured to reduce the pressure inthe MRS Section 420 to less than about 1.5 millibars (e.g., about 1millibar or less). The low-pressure vacuum created by the Vacuum Pump430 in the MRS Section 420 may remove, for example: (1) volatileorganics present in the melted polymer as the melted polymer passesthrough the MRS Section 420; and/or (2) at least a portion of anyinterstitial water that was present in the wet flakes when the wetflakes entered the MRS Extruder 400. In various embodiments, thelow-pressure vacuum removes substantially all (e.g., all) of the waterand contaminants from the polymer stream.

In a particular example, the Vacuum Pump 430 comprises three mechanicallobe vacuum pumps (e.g., arranged in series) to reduce the pressure inthe chamber to a suitable level (e.g., to a pressure of about 1.0millibar). In other embodiments, rather than the three mechanical lobevacuum pump arrangement discussed above, the Vacuum Pump 430 includes ajet vacuum pump fit to the MRS extruder. In various embodiments, the jetvacuum pump is configured to achieve about 1 millibar of pressure in theinterior of the MRS section 420 and about the same results describedabove regarding a resulting intrinsic viscosity of the polymer melt. Invarious embodiments, using a jet vacuum pump can be advantageous becausejet vacuum pumps are steam powered and therefore substantiallyself-cleaning (e.g., self-cleaning), thereby reducing the maintenancerequired in comparison to mechanical lobe pumps (which may, for example,require repeated cleaning due to volatiles coming off and condensing onthe lobes of the pump). In a particular embodiment, the Vacuum Pump 430is a jet vacuum pump is made by Arpuma GmbH of Bergheim, Germany.

In particular embodiments, after the molten polymer is run through themulti-stream MRS Section 420, the streams of molten polymer arerecombined and flow into the MRS extruder's second single screw section440. In various embodiments, the single stream of molten polymer is nextrun through a filtration system 450 that includes at least one filter.In a particular embodiment, the filtration system 450 includes twolevels of filtration (e.g., a 40 micron screen filter followed by a 25micron screen filter). Although, in various embodiments, water andvolatile organic impurities are removed during the vacuum process asdiscussed above, particulate contaminates such as, for example, aluminumparticles, sand, dirt, and other contaminants may remain in the polymermelt. Thus, this filtration step may be advantageous in removingparticulate contaminates (e.g., particulate contaminates that were notremoved in the MRS Section 420).

In particular embodiments, a viscosity sensor 460 (see FIG. 4) is usedto sense the melt viscosity of the molten polymer stream following itspassage through the filtration system 450. In various embodiments, theviscosity sensor 460, measures the melt viscosity of the stream, forexample, by measuring the stream's pressure drop across a known area. Inparticular embodiments, in response to measuring an intrinsic viscosityof the stream that is below a predetermined level (e.g., below about 0.8g/dL), the system may: (1) discard the portion of the stream with lowintrinsic viscosity; and/or (2) lower the pressure in the MRS Section420 in order to achieve a higher intrinsic viscosity in the polymermelt. In particular embodiments, decreasing the pressure in the MRSSection 420 is executed in a substantially automated manner (e.g.,automatically) using the viscosity sensor in a computer-controlledfeedback control loop with the vacuum section 430.

In particular embodiments, removing the water and contaminates from thepolymer improves the intrinsic viscosity of the recycled PET polymer byallowing polymer chains in the polymer to reconnect and extend the chainlength. In particular embodiments, following its passage through the MRSSection 420 with its attached Vacuum Pump 430, the recycled polymer melthas an intrinsic viscosity of at least about 0.79 dL/g (e.g., of betweenabout 0.79 dL/g and about 1.00 dL/g). In particular embodiments, passagethrough the low pressure MRS Section 420 purifies the recycled polymermelt (e.g., by removing the contaminants and interstitial water) andmakes the recycled polymer substantially structurally similar to (e.g.,structurally the same as) pure virgin PET polymer. In particularembodiments, the water removed by the vacuum includes both water fromthe wash water used to clean the recycled PET bottles as describedabove, as well as from unreacted water generated by the melting of thePET polymer in the single screw heater 410 (e.g., interstitial water).In particular embodiments, the majority of water present in the polymeris wash water, but some percentage may be unreacted water.

In particular embodiments, the resulting polymer is a recycled PETpolymer (e.g., obtained 100% from post-consumer PET products, such asPET bottles or containers) having a polymer quality that is suitable foruse in producing PET carpet filament using substantially only (e.g.,only) PET from recycled PET products.

Step 3: Purified PET Polymer Fed into Spinning Machine to be Turned intoCarpet Yarn

In particular embodiments, after the recycled PET polymer has beenextruded and purified by the above-described extrusion process, theresulting molten recycled PET polymer is fed directly into a BCF (or“spinning”) machine 500 that is configured to turn the molten polymerinto bulked continuous filament. For example, in various embodiments,the output of the MRS extruder 400 is connected substantially directly(e.g., directly) to the input of the spinning machine 500 so that moltenpolymer from the extruder is fed directly into the spinning machine 500.This process may be advantageous because molten polymer may, in certainembodiments, not need to be cooled into pellets after extrusion (as itwould need to be if the recycled polymer were being mixed with virginPET polymer). In particular embodiments, not cooling the recycled moltenpolymer into pellets serves to avoid potential chain scission in thepolymer that might lower the polymer's intrinsic viscosity.

In particular embodiments, the spinning machine 500 extrudes moltenpolymer through small holes in a spinneret in order to produce carpetyarn filament from the polymer. In particular embodiments, the moltenrecycled PET polymer cools after leaving the spinneret. The carpet yarnis then taken up by rollers and ultimately turned into filaments thatare used to produce carpet. In various embodiments, the carpet yarnproduced by the spinning machine 500 may have a tenacity between about 3gram-force per unit denier (gf/den) and about 9 gf/den. In particularembodiments, the resulting carpet yarn has a tenacity of at least about3 gf/den.

In particular embodiments, the spinning machine 500 used in the processdescribed above is the Sytec One spinning machine manufactured byOerlika Neumag of Neumuenster, Germany. The Sytec One machine may beespecially adapted for hard-to-run fibers, such as nylon orsolution-dyed fibers, where the filaments are prone to breakage duringprocessing. In various embodiments, the Sytec One machine keeps the runsdownstream of the spinneret as straight as possible, uses only onethreadline, and is designed to be quick to rethread when there arefilament breaks.

Although the example described above describes using the Sytec Onespinning machine to produce carpet yarn filament from the polymer, itshould be understood that any other suitable spinning machine may beused. Such spinning machines may include, for example, any suitableone-threadline or three-threadline spinning machine made by OerlikaNeumag of Neumuenster, Germany or any other company.

In various embodiments, the improved strength of the recycled PETpolymer generated using the process above allows it to be run at higherspeeds through the spinning machine 500 than would be possible usingpure virgin PET polymer. This may allow for higher processing speedsthan are possible when using virgin PET polymer.

SUMMARY OF EXEMPLARY PROCESS

FIG. 5 provides a high-level summary of the method of manufacturingbulked continuous filament described above. As shown in the figure, themethod begins at Step 602, where recycled PET bottles are ground into agroup of flakes. Next, at Step 604, the group of flakes is washed toremove contaminants from the flakes' respective outer surfaces. Next, atStep 606, the group of flakes is scanned (e.g., using one or more of themethods discussed above) to identify impurities, including impureflakes. These impurities, and impure flakes, are then removed from thegroup of flakes.

Next, at Step 608, the group of flakes is passed through an MRS extruderwhile maintaining the pressure within an MRS portion of the extruderbelow about 1.5 millibars. At Step 610, the resulting polymer melt ispassed through at least one filter having a micron rating of less thanabout 50 microns. Finally, at Step 612, the recycled polymer is formedinto bulked continuous carpet filament, which may be used in producingcarpet. The method then ends at Step 614.

ALTERNATIVE EMBODIMENTS

In particular embodiments, the system may comprise alternativecomponents or perform alternative processes in order to producesubstantially continuous BCF from 100% recycled PET, or other recycledpolymer. Exemplary alternatives are discussed below.

Non-MRS Extrusion System

In particular embodiments, the process may utilize a polymer flowextrusion system other than the MRS Extruder described above. Thealternative extrusion system may include for example, a twin screwextruder, a multiple screw extruder, a planetary extruder, or any othersuitable extrusion system. In a particular embodiment, the process mayinclude a plurality of any combination of any suitable conical screwextruders (e.g., four twin screw extruders, three multiple screwextruders, etc.).

Making Carpet Yarn from 100% Recycled Carpet

In particular embodiments, the process described above may be adaptedfor processing and preparing old carpet (or any other suitablepost-consumer product) to produce new carpet yarn comprising 100%recycled carpet. In such embodiments, the process begins by grinding andwashing recycled carpet rather than recycled PET bottles. In variousembodiments where old carpet is converted into new carpet yarncomprising 100% recycled carpet, the process may comprise additionalsteps to remove additional materials or impurities that may be presentin recycled carpet that may not be present in recycled PET bottles(e.g., carpet backing, adhesive, etc.).

Other Sources of Recycled PET

In various embodiments, the process described above is adapted forprocessing recycled PET from any suitable source (e.g., sources otherthan recycled bottles or carpet) to produce new carpet yarn comprising100% recycled PET.

The Use of a Crystallizer as Part of BCF Process

In various embodiments, the process for producing recycled BCF mayfurther include a crystallizing step that utilizes one or more PETcrystallizers. In particular embodiments, the system is configured toperform the crystallization step on the ground flakes prior to runningthe flakes through the one or more extruders (e.g., single screwextruder, MRS extruder, etc.). In particular embodiments, the PETcrystallizer comprises a housing, a hopper screw (e.g., an auger)disposed at least partially within the housing, a stirring apparatus,one or more heating elements, and one or more blowers.

Hopper Screw

In particular embodiments, the hopper screw comprises any suitable screwconveyor (e.g., such as an Archimedes' screw) for moving liquid orgranular materials (e.g., such as PET flakes). In various embodiments,the hopper screw comprises a substantially cylindrical shaft and ahelical screw blade disposed along at least a portion of the cylindricalshaft. In particular embodiments, the substantially cylindrical shaft isconfigured to rotate the screw blade, causing that hopper screw to movematerial (e.g., the PET flakes) along the cylindrical shaft and into thecrystallizer housing. In other embodiments, the hopper screw comprisesany other suitable screw conveyer such as, for example, a shaftlessspiral. In embodiments in which the hopper screw comprises a shaftlessspiral, the shaftless spiral may be substantially fixed at one end andfree at the other end and configured to be driven at the fixed end. Invarious embodiments, the hopper screw is disposed at least partiallywithin the crystallizer housing.

In various embodiments, the hopper screw is configured to feed PETflakes into the crystallizer. In various embodiments, the PETcrystallizer is configured to feed the PET flakes into the crystallizerusing the hopper screw relatively slowly.

One or More Heating Elements

In various embodiments, the crystallizer comprises one or more heatingelements for raising a temperature within the crystallizer. Inparticular embodiments, the one or more heating elements comprise one ormore electric heating elements, one or more gas-fired heating elements,or any other suitable heating elements. In some embodiments, the one ormore heating elements may be substantially electrically powered. Invarious embodiments, the one or more heating elements comprise one ormore infra-red heating elements. In other embodiments, the one or moreheating elements may utilize natural gas such, for example, propane. Inparticular embodiments, the one or more heating elements are configuredto raise a temperature within the crystallizer to between about 100degrees Fahrenheit and about 180 degrees Fahrenheit. In still otherembodiments, the one or more heating elements are configured to raise atemperature within the crystallizer to between about 100 degrees Celsiusand 180 degrees Celsius. In some embodiments, the one or more heatingelements are configured to maintain a temperature within thecrystallizer that is substantially about a maximum crystallizationtemperature of PET. In particular embodiments, the maximumcrystallization temperature of PET is between about 140 degrees Celsiusand about 230 degrees Celsius.

One or More Blowers

In various embodiments, the crystallizer further comprises one or moreblowers configured to blow air over the flakes as the flakes passesthrough the crystallizer. In particular embodiments, the one or moreblowers comprise any suitable blowers for moving air substantiallyacross a surface area of the flakes as the flakes pass through thecrystallizer. For example, in some embodiments, the one or more blowerscomprise one or more suitable fans or other suitable mechanisms formoving air. In various embodiments, the one or more blowers areconfigured to blow air that has been at least partially heated by theone or more heating elements. In particular embodiments, the one or moreblowers are configured to blow air having a temperature of at leastabout 140 degree Fahrenheit. In another particular embodiments, the oneor more blowers are configured to blow air having a temperature of atleast about 140 degree Celsius. In other embodiments, the one or moreblowers are configured to maintain the temperature in the crystallizerbetween about 140 degrees Fahrenheit and about 180 degrees Fahrenheit.In some embodiments, the one or more blowers are configured to blow hotair from a bottom portion of the crystallizer and draw air from an upperportion of the crystallizer.

Stirring Apparatus

In various embodiments, the crystallizer comprises a stirring apparatusthat comprises any suitable apparatus for stirring the PET flakes whilethe PET flakes are passing through the crystallizer. In variousembodiments, the stirring apparatus may be operated, for example, by anysuitable gear motor. In a particular embodiment, the stirring apparatuscomprises a suitable rod or other suitable mechanism mounted to rotate,or otherwise stir the PET flakes as the PET flakes are passing throughthe crystallizer. In other embodiments, the stirring apparatus maycomprise any suitable tumbler, which may, for example, comprise a drummounted to rotate via the gear mother such that the PET flakes are atleast partially stirred and/or agitated while the PET flakes are withinthe drum. In still other embodiments, the stirring apparatus comprisesone or more screws and/or augers configured to rotate and stir the PETflakes. In particular embodiments, the stirring apparatus comprises thehopper screw.

As may be understood from this disclosure, the stirring apparatus isconfigured to agitate and/or stir the PET flakes as the one or moreblowers blow air heated by the one or more heating elements across thePET flakes. In particular embodiments, the stirring apparatus isconfigured to at least partially reduce agglomeration (e.g., sticking orclumping of the flake) while the flake is at least partiallycrystallizing in the crystallizer.

In particular embodiments, the crystallizer at least partially dries thesurface of the PET flakes. In various embodiments, the PET crystallizeris configured to reduce a moisture content of the PET flakes to about 50ppm. In other embodiments, the PET crystallizer is configured to reducea moisture content of the PET flakes to between about 30 and about 50ppm.

In various embodiments, the use of drier flakes may enable the system torun the flakes through the MRS extruder more slowly, which may allow forhigher pressure within the MRS extruder during extrusion (e.g., mayenable the system to maintain a higher pressure within the MRS extruder,rather than very low pressure). In various embodiments of the process,the pressure regulation system may be configured to maintain a pressurewithin the MRS extruder of between about 0 millibars and about 25millibars. In particular embodiments, such as embodiments in which thePET flakes have been run through a crystallizer before being extruded inthe MRS extruder, the pressure regulation system may be configured tomaintain a pressure within the MRS extruder of between about 0 and about18 millibars. In other embodiments, the pressure regulation system maybe configured to maintain a pressure within the MRS extruder betweenabout 0 and about 12 millibars. In still other embodiments, the pressureregulation system may be configured to maintain a pressure within theMRS extruder between about 0 and about 8 millibars. In still otherembodiments, the pressure regulation system may be configured tomaintain a pressure within the MRS extruder between about 5 millibarsand about 10 millibars. In particular embodiments, the pressureregulation system may be configured to maintain a pressure within theMRS extruder at about 5 millibars, about 6 millibars, about 7 millibars,about 8 millibars, about 9 millibars, or about any suitable pressurebetween about 0 millibars and about 25 millibars. It should beunderstood that any numerical ranges listed herein include a disclosureof each distinct number within those numerical ranges. For example, thedisclosure of a range of between about 10 millibars and about 15millibars, should also be understood to constitute a disclosure of about11 millibars, about 12 millibars, about 13 millibars, about 13.5millibars, etc. . . .

In particular embodiments, the process may utilize any suitable infraredPET crystallizer. In such embodiments, the crystallizer may comprise oneor more infrared heating elements for at least partially drying at leasta portion of a surface of the PET flakes. In various embodiments, thecrystallizer may be configured to process (e.g., crystallize and/or dry)between about 180 and about 4,000 pounds of flake per hour. In variousembodiments the PET crystallizer is configured to cause infrared energyto penetrate up to about 5 mm into the PET flakes. In variousembodiments, the infrared energy penetration may cause the PET flakes todry and/or crystallizer more quickly than a traditional radiant heatingsystem. Additionally, an infrared PET crystallizer may use less energythat non infra-red PET crystallizers. In various embodiments, theinfrared PET crystallizer is configured to produce infrared energyhaving a wavelength between about 1 and about 2 microns. In variousembodiments, infrared energy in this range of wavelengths is suited toan absorption spectrum of both PET and water, which may, for example,enable the infrared energy to penetrate more deeply into the PET thanother wavelengths.

In particular embodiments, the crystallizer causes the flakes to atleast partially reduce in size, which may, for example, reduce apotential for the flakes to clump together. In particular embodiments,the crystallizer may particularly reduce stickiness of larger flakes,which may, for example, include flakes comprising portions of the groundPET bottles which may be thicker than other portions of the PET bottles(e.g., flakes ground from a threaded portion of the PET bottle on whicha cap would typically be screwed).

Use of Curbside Recycling v. Deposit Bottles in Process

In various embodiments, the system is configured to utilize recycled PETof varying quality in the process described above. For example, invarious embodiments, the system is configured to produce bulkedcontinuous carpet filament from PET derived from PET bottles sourcedfrom curbside recycling sources (e.g., PET bottles that were collectedas part of a general bulk recycling program or other recycling source)and/or deposit PET bottles (e.g., bottles returned as part of a depositprogram). In various embodiments, Curbside recycled bottles may requiremore thorough processing in order to produce bulked continuous filament,as curbside recycled PET bottles may be mixed in with and otherwiseinclude contaminants such as, for example: other recyclable goods (e.g.,paper, other plastics, etc.), garbage, and other non-PET bottle itemsdue to imperfect sorting of recycled goods or for any other reason.Deposit PET bottles may include PET bottles with fewer unwantedcontaminants due in part because deposit PET bottles may be collectedseparately from other recyclable or disposable goods.

In various embodiments, curbside recycled PET bottles acquired duringparticular times of a particular year may include more impurities andother contaminants than at other times of the year. For example,curbside recycled PET bottles collected during summer months maycomprise a higher percentage of clear PET bottles (e.g., water bottles)at least in part due to additional consumer water consumption duringsummer months.

In various embodiments, the system described above may be configured toadjust particular components of the process based at least in part onthe source of recycled PET being used to produce the bulked continuouscarpet filament. For example, because deposit PET bottles include fewerimpurities that need to be removed during the initial cleaning andsorting phases of the process, the pressure regulation system may beconfigured to maintain a pressure within the MRS extruder that is higherthan a pressure that it would be configured to maintain for PET flakederived from curbside recycled PET bottles. In a particular embodiment,the pressure regulation system may be configured to maintain a pressurewithin the MRS extruder of between about 0 millibars and about 12millibars when flakes derived from deposit PET bottles are passingthrough the MRS extruder. In still other embodiments, the pressureregulation system may be configured to maintain a pressure within theMRS extruder of between about 5 millibars and about 10 millibars in suchinstances.

In various embodiments, the system is configured to determine a suitablepressure at which to maintain the pressure within the MRS extruder basedat least in part on the source of the recycled PET. In otherembodiments, the system is configured to omit one or more of the stepsabove or include one or more additional steps to the steps describedabove based at least in part on the source of the recycled PET.

CONCLUSION

Many modifications and other embodiments of the invention will come tomind to one skilled in the art to which this invention pertains havingthe benefit of the teachings presented in the foregoing descriptions andthe associated drawings. For example, although the vacuum systemdiscussed above is described as being configured to maintain thepressure in the open chambers of the MRS extruder to about 1 mbar, inother embodiments, the vacuum system may be adapted to maintain thepressure in the open chambers of the MRS extruder at pressures greaterthan, or less than, 1 mbar. For example, the vacuum system may beadapted to maintain this pressure at between about 0.5 mbar and about 12mbar.

Similarly, although various embodiments of the systems described abovemay be adapted to produce carpet filament from substantially onlyrecycled PET (so the resulting carpet filament would comprise, consistof, and/or consist essentially of recycled PET), in other embodiments,the system may be adapted to produce carpet filament from a combinationof recycled PET and virgin PET. The resulting carpet filament may, forexample, comprise, consist of, and/or consist essentially of betweenabout 80% and about 100% recycled PET, and between about 0% and about20% virgin PET.

Also, while various embodiments are discussed above in regard toproducing carpet filament from PET, similar techniques may be used toproduce carpet filament from other polymers. Similarly, while variousembodiments are discussed above in regard to producing carpet filamentfrom PET, similar techniques may be used to produce other products fromPET or other polymers.

In addition, it should be understood that various embodiments may omitany of the steps described above or add additional steps.

In light of the above, it is to be understood that the invention is notto be limited to the specific embodiments disclosed and thatmodifications and other embodiments are intended to be included withinthe scope of the appended claims. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor the purposes of limitation.

We claim:
 1. A method of recycling a PET-containing material,comprising: providing a polymer crystallizer comprising at least oneheating element, and at least one blower; providing a multi-rotatingscrew (MRS) extruder having an MRS section comprising a plurality ofsatellite screws, each of the plurality of satellite screws being atleast partially housed within a respective extruder barrel and mountedto rotate about its respective central axis; providing a vacuum pump influid communication with the MRS section; grinding and washing thePET-containing material; heating the PET-containing material in thecrystallizer to at least partially dry the PET-containing material;shearing the PET-containing material in the MRS extruder to produce aPET-containing melt; increasing a surface area of the PET-containingmelt by distributing the PET-containing melt across the plurality ofsatellite screws in the MRS extruder; drawing off vapors from thePET-containing melt by reducing the pressure in the MRS section with thevacuum pump; collating the PET-containing melt in the MRS extruder; andextruding a recycled PET-containing material.
 2. The method of claim 1,wherein the PET-containing material is either old carpet or recycled PETbottles.
 3. The method of claim 1, wherein the pressure is reduced tobetween 0 and 25 millibars.
 4. The method of claim 1, wherein the vaporsare moisture from interstitial water and volatile organic impurities. 5.The method of claim 5, wherein the moisture in the PET-containing meltis reduced to below about 50 ppm.
 6. The method of claim 1, wherein thevacuum pump is a jet vacuum pump.
 7. A method of purifying a PETpolymer, comprising: grinding and washing a PET-containing material;heating the PET-containing material in a crystallizer to at leastpartially dry the PET-containing material, wherein the crystallizercomprises at least one heating element, and at least one blower; meltingthe PET-containing material in an MRS extruder, wherein the MRS extrudercomprises a plurality of satellite screws, each of the plurality ofsatellite screws being at least partially housed within a respectiveextruder barrel and mounted to rotate about its respective central axis,a viscosity monitor, and a pressure regulation system; increasing asurface area of the melted PET-containing material by distributing thePET-containing material across the plurality of satellite screws in theMRS extruder; monitoring a viscosity of the melted PET-containingmaterial within the MRS extruder; regulating a pressure within the MRSextruder with the pressure regulation system in response to an intrinsicviscosity of the PET-containing melt; filtering the meltedPET-containing material through a filter; and extruding a purified PETpolymer.
 8. The method of claim 7, wherein the PET-containing materialis either old carpet or recycled PET bottles.
 9. The method of claim 7,wherein the pressure is reduced to between 0 and 25 millibars.
 10. Themethod of claim 7, wherein the pressure regulation system comprises avacuum pump.
 11. The method of claim 10, wherein the vacuum pump is ajet vacuum pump.
 12. The method of claim 7, wherein the at least oneheating element is configured to maintain a temperature within thecrystallizer to between about 100 degrees Fahrenheit and about 180degrees Fahrenheit.
 13. The method of claim 7, wherein the at least oneheating element is configured to maintain a temperature within thecrystallizer to between about 100 degrees Celsius and 180 degreesCelsius.
 14. The method of claim 7, wherein the filter comprises a 40micron screen filter followed by a 25 micron screen filter.
 15. A methodof using a purified polymer to produce bulked continuous filament,comprising: stirring and heating a plurality of washed polymer flakes ina crystallizer to substantially remove surface moisture from theplurality of washed polymer flakes; directly feeding the plurality ofpolymer flakes to an extruder and melting the plurality of polymerflakes to produce a polymer melt, wherein the extruder comprises aplurality of satellite screws, each of the plurality of satellite screwsbeing at least partially housed within a respective extruder barrel andmounted to rotate about its respective central axis; expanding a surfacearea of the polymer melt by separating the polymer melt into a pluralityof streams of polymer melt, wherein each stream of polymer melt isassociated with one satellite screw of the plurality of satellitescrews; removing at least some water and volatile organic impuritiesfrom the plurality of streams of polymer melt by reducing a pressurewithin the extruder; recombining the streams of polymer melt; filteringthe recombined polymer melt through a filter to produce a purifiedpolymer melt; and directly feeding the purified polymer melt into aspinning machine wherein the purified polymer melt is spun into bulkedcontinuous filament.
 16. The method of claim 15, wherein the pressureregulation system is configured to maintain the pressure to between 0and 25 millibars.
 17. The method of claim 15, wherein the pressureregulation system is configured to maintain the pressure to between 0and 18 millibars.
 18. The method of claim 15, wherein the pressureregulation system comprises a vacuum pump.
 19. The method of claim 18,wherein the vacuum pump is a jet vacuum pump.
 20. The method of claim15, wherein the filter comprises a 40 micron screen filter followed by a25 micron screen filter.